1. Field of The Invention
The present invention relates generally to a height control system for a vehicle. More particularly, the invention is directed to a height control system which serves to level a vehicle body after an ignition switch is turned off to deactivate a fluid power source for suspension units.
2. Description of The Background Art
Japanese Utility Model Publication No. 58-95307 discloses a height control system for a vehicle utilizing electronically controlled air suspension units. These air suspension units include air chambers filled with compressed air and shock absorbers for adjusting height levels between a vehicle body and wheels respectively. The height level adjustment is accomplished by supplying compressed air from an air source to the air chambers through height control valves or draining the compressed air in the air chambers for leveling the vehicle body at a standard height value.
However, in such a conventional height control system, operating a compressor for supplying air to air suspensions to increase a height level is undesirable after an ignition switch is turned off to stop an engine since a battery may be undesirably drained. For example, when height difference between left and right wheels exists after the ignition switch is turned off, the conventional height control system drains compressed air from an air chamber of higher pressure to modify a higher height level to agree with a lower height level, reducing the height difference between the left and right wheels. Therefore, when the lower height level is below a standard height value, when the height difference is neutralized, height levels at both left and right wheels result in a level undesirably lower than the standard height value.